Digital video camera

ABSTRACT

A digital video camera, including a heat management system, which includes at least one inlet and at least one outlet in the housing to enable air to flow through the housing. The heat management system also includes a first heat sink thermally connected to an image sensor(s), and a second heat sink thermally connected to a data processing unit(s), and a centrifugal fan. The centrifugal fan is configured to draw air into the front of the fan in an axial direction and push air radially out in a sideways direction, whereby air travels through the inlet(s) over the first heat sink and then over the second heat sink to the outlet(s).

PRIORITY DATA

This application claims priority to Australian Application No.2015901286, filed Apr. 10, 2015, and entitled “Digital Video Camera,”the disclosure of which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to digital video cameras and theirconstruction.

BACKGROUND OF THE INVENTION

During editing for cinema and television, footage taken from a number ofdifferent cameras can be edited together in a single scene. To ensurefootage from different cameras match it is important that each of thecameras used are capable of outputting footage of equal quality, forexample in relation to resolution, dynamic range, frame rate and colour.If the quality is too different, the transitions between footage fromdifferent cameras will be obvious to the viewer and not to a standardexpected for cinematographic use.

In some situations, there is a requirement to use a video camera that iscapable of fitting in a confined space or location that a standardcamera cannot, such as in a refrigerator or other enclosure; or mountedto a drone for aerial footage. Whilst small sized cameras have beenavailable in the past, there has been a limitation on the quality of theimage produced by such cameras, making their utility in high qualitycinema and television applications limited.

One of the problems faced by a digital video camera designer that limitsthe ability to make compact cinema-quality cameras is the need to usecertain high powered components. These high powered components generatea large amount of heat, such that if they are confined in a smallhousing they will overheat and the image will deteriorate and it ispossible that the camera will fail. This problem is becoming morepronounced as the desired image resolution and quality increases.

Accordingly there is a need for a video camera design that addresses theabove drawbacks of the prior art or at least provides a usefulalternative to the conventional cinematographic video camera design.

Reference to any prior art in the specification is not an acknowledgmentor suggestion that this prior art forms part of the common generalknowledge in any jurisdiction or that this prior art could reasonably beexpected to be understood, regarded as relevant, and/or combined withother pieces of prior art by a skilled person in the art.

SUMMARY OF THE INVENTION

In one form, a video camera made in accordance with an embodiment of thepresent invention provides cooling across the camera housing using acentrifugal fan in combination with two heat sinks. A first heat sink isthermally connected to an image sensor and the second heat sink isthermally connected to a data processing unit. The data processing unitproduces more heat than the image sensor. The direction of air flow issuch that air flows across the first heat sink before flowing across thesecond heat sink.

According to a first aspect, the present invention provides a digitalvideo camera, including:

a housing;

at least one image sensor to convert light into electrical signals;

an optical system associated with the image sensor;

a lens mount for releasably engaging a lens or other optical module;

data processing unit(s) to process image data received from the imagesensor(s); and

a heat management system, which includes:

-   -   at least one inlet and at least one outlet in the housing to        enable air to flow through the housing;    -   an inlet-side heat sink thermally connected to the image        sensor(s), and an outlet-side heat sink thermally connected to        the data processing unit(s), said inlet-side heat sink being        separated from the outlet-side heat sink; and    -   a fan configured to draw air into the housing through the        inlet(s) over the inlet-side heat sink and push air over the        outlet-side heat sink out the outlet(s);

wherein the fan is a centrifugal fan, such that air is drawn into thefront of the fan and pushed out one side of the fan.

According to a second aspect, the present invention provides a digitalvideo camera, including:

a housing;

at least one image sensor to convert light into electrical signals;

an optical system associated with the image sensor;

a lens mount for releasably engaging a lens or other optical module;

data processing unit(s) to process image data received from the imagesensor(s); and

a heat management system, which includes:

-   -   at least one inlet and at least one outlet in the housing to        enable air to flow through the housing;    -   a first heat sink thermally connected to the image sensor(s),        and a second heat sink thermally connected to the data        processing unit(s); and    -   a centrifugal fan configured to draw air into the front of the        fan in a generally axial direction and push air radially out in        a sideways direction, whereby air is drawn into the housing        through the inlet(s) over the first heat sink and then over the        second heat sink out the outlet(s).

The first heat sink is preferably an inlet-side heat sink. The secondheat sink is preferably an outlet-side heat sink.

The first/inlet-side heat sink is preferably separated from thesecond/outlet-side heat sink.

The first/inlet-side heat sink may additionally be thermally connectedto a processor, which may be associated with the image sensor.

The housing is preferably provided as two components, a front housingcomponent and a rear housing component. The front housing component maybe made from magnesium. The rear housing component may be made from aplastic, such as a thermoplastic polymer, for example ABS (Acrylonitrilebutadiene styrene).

The heat sinks may be made from die cast aluminum, however it will beappreciated that other materials, such as magnesium may be used andalternative manufacturing techniques may be used, such as forging.

It is advantageous that the inlet(s) and outlet(s) are provided on therear housing component. The housing is generally rectangular, having afront side, a rear side, a top side, a bottom side and a left and rightside. The inlet(s) and outlet(s) are preferably located on opposingsides of the housing. The inlet(s) and outlet(s) may be provided on thesame side of the housing. In some embodiments the inlet(s) and outlet(s)may be on adjacent sides of the housing. In an embodiment, separateinlets may be provided on opposite sides of the housing and theoutlet(s) may be provided on one of those sides. The inlet(s) andoutlet(s) are preferably openings in the housing. The housing isadvantageously shaped such that the openings cannot be obstructed bylaying the camera on either side.

It is also advantageous that the rear housing component contains thedata processing unit(s). The data processing unit(s) preferablycomprises a main printed circuit board (PCB), which may include a fieldprogrammable gate array (FPGA).

The rear housing component also preferably includes thesecond/outlet-side heat sink.

External mounting arrangements are provided, enabling the digital videocamera to be mounted to external accessories, such as tripods or arms.The mounting arrangements are preferably provided on the front housingcomponent, as the front housing component is typically made from astronger material than the rear housing component. The mountingarrangement may be provided on the top and/or bottom of the housing.

The front housing component also advantageously includes one or moremicrophones, positioned such that they are mechanically isolated fromthe fan to minimise noise transmission through camera to themicrophone's transducer.

The thermal connection between the first/inlet-side heat sink and theimage sensor and the thermal connection between the second/outlet-sideheat sink and the data processing unit draws heat away from the imagesensor and the data processing unit respectively. The heat managementsystem can include a cooling subsystem in some embodiments to move heatgenerated by the image sensor. The cooling subsystem can include a heattransfer element. The heat transfer element could include an activecooler, such as a Peltier cooler or heat pipe or the like. The imagesensor is typically mounted to a substrate, such as a sensor PCB. ThePeltier cooler may be located between the image sensor and thefirst/inlet-side heat sink. Thus, the thermal connection between theimage sensor and the first/inlet-side heat sink can be direct orindirect.

The fan is preferably located between the first/inlet-side heat sink andthe second/outlet-side heat sink. The fan may be located in the flowpath after the first/inlet-side heat sink and the second/outlet-sideheat sink. The main internal components may be stacked back to back in asingle direction, such that they are generally aligned in series. Thecentrifugal fan blows air in a direction that is sideways to the stackdirection.

A spacer is preferably provided to physically separate thefirst/inlet-side heat sink and the second/outlet-side heat sink. Thespacer may be made from a low thermally conductive material, such asplastic, to provide a thermal break between the first/inlet-side heatsink and the second/outlet-side heat sink. The spacer surrounds the fanand may include a rim that extends around the inlet-side of the spacer.The rim assists in trapping the air and pressurising the air at the tipof the fan blades to direct the air flow in the direction of theoutlet(s), by restricting air flow in other directions. The spacer maybe attached to either the first/inlet-side heat sink or thesecond/outlet-side heat sink. The first/inlet-side heat sink ispreferably attached to the front housing component. The front housingcomponent and rear housing component may be separated so that the fancan be exposed for removal allowing for repair or replacement.

The image sensor and the optical system may constitute an image capturemodule. The image capture module may be a sealed module.

Each image sensor may have an imaging plane, said image sensor beingmounted within the housing such that the imaging plane lies at apredefined distance from a plane of a mounting face of the lens mount.The at least one image sensor may be mounted to the image capture modulevia an adjustable mounting structure to allow adjustment of the positionof the at least one image sensor position with respect to the housingand lens mount. The at least one image sensor may be mounted to asubstrate, such as the sensor PCB, wherein the adjustable mountingstructure includes a series of adjustment screws holding the substrateto the housing. Said adjustable mounting structure may further includeone or more spacers positioned between the substrate and the housing toset the predefined distance between the imaging plane and the plane ofthe mounting face of the lens mount.

A power supply subsystem may be mounted to the housing to supply power.Advantageously an external battery is mounted to the rear wall of therear housing component. Alternatively power supply may be provided via acable.

Preferably there is provided a user interface subsystem to enable theuser to control the image sensor. This may be associated with thehousing or may be provided remotely. The user interface subsystempreferably includes buttons and/or lights or a multifunction indicator.

A data storage subsystem may be provided to store data derived from theimage sensor. The data storage subsystem can include a removable memorymodule. Preferably the removable memory module is a memory card.

An input and/or output subsystem is typically provided to enable data orelectrical connection to another device.

In a preferred form the camera includes a data communication connectionbetween the data processing unit and another module to exchange databetween the data processing unit and the other module. Said data couldbe, without limitation, image data received from the image sensor;control data for controlling the operation of the optical system or lensconnected thereto; sensing data derived from the image sensor, or theoptical system or lens connected thereto.

The lens mount preferably includes a coupling to releasably engage alens or other optical module thereto. The lens mount can have a mountingface against which a mating surface of a lens abuts.

One or more light transmissive elements may be provided in front of andcovering the image sensor. The one or more light transmissive elementscould be any type of light transmissive element including but notlimited to:

One or more lenses,

One or more filters,

One or more polarisers,

A light transmissive cover.

Preferably, the optical element covering the image sensor is spacedapart from the image sensor and sealed to the housing.

As will be appreciated, direct contact in the context of heattransmission can include contact via an intermediate substance ormaterial that aids thermal transmission between components, such asthermal grease or the like.

As used herein, except where the context requires otherwise, the term“comprise” and variations of the term, such as “comprising”, “comprises”and “comprised”, are not intended to exclude further additives,components, integers or steps.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention and further embodiments of theaspects described in the preceding paragraphs will become apparent fromthe following description, given by way of example and with reference tothe accompanying drawings, in which:

FIG. 1 is a front perspective view of a digital video camera accordingto a first embodiment of the invention;

FIG. 2 is a rear perspective view of the digital video camera of FIG. 1;

FIG. 3 is a front perspective view of a digital video camera accordingto a second embodiment of the invention;

FIG. 4 is an exploded front perspective view of the digital video cameraof FIG. 1;

FIG. 5 is an exploded rear perspective view of the first/inlet-side heatsink, the spacer, the fan and the second/outlet-side heat sink;

FIG. 6 is a bottom cross-sectional view through the centre of thedigital video camera shown in FIG. 1;

FIG. 7 is a side cross-section view through the centre of the digitalvideo camera shown in FIG. 1, looking towards the inlet side;

FIG. 8 is a perspective side cross-section view through the centre ofthe digital video camera shown in FIG. 1, looking towards the inletside;

FIG. 9 is a perspective top cross-section view through the centre of thedigital video camera shown in FIG. 1;

FIG. 10 is a view of a camera housing with an internal configurationaccording to a second embodiment; and

FIG. 11 is a view of a camera housing with an internal configurationaccording to a third embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 illustrates a digital video camera 100 according to a firstembodiment. The camera 100 is generally rectangular and formed from twohousing components, a front housing component 102 and a rear housingcomponent 104. The front housing component 102 has a front side thatincludes a lens mount 106 including a mechanical structure configured toreceive a mechanical coupling on a lens to be fitted to the mount 106.In one form the mechanical structure is arranged to receive a bayonetstyle mount. The lens mount 106 additionally includes a series ofelectrical and data contacts 108. A button 110 is also provided fordisengaging a lens from the lens mount 106. In embodiments of thiscamera, the lens mount may be made according to a standard lens mountconfiguration, such as an EF mount, a MFT mount, or other lens mount.

The front housing component 102 also includes a central bore 112 foradmitting light to the optical system mounted therein. The inside wallof the bore 112 includes a series of ribs to prevent reflections of offaxis unfocussed light from the inside surface 114 of the bore 112 fromreaching the image sensor. Also provided, but not visible, is an outercover, in the form of an optical filter to seal the sensitive parts ofthe front housing component 102.

At the top of the front housing component 102 is a light indicator 116,which may be an RGB LED multifunction indicator. In the embodiment shownin FIG. 1, there is also provided a user interface button. The userinterface button is a record button 118, which actuates recording by thecamera. This button 118 is easily accessible by a user from the front ofthe camera 100.

The front housing component 102 is preferably made from magnesium,giving it strength, whilst being light. On the top side and bottom sideof the front housing component 102 there is provided a number ofmounting points 119. The mounting points 119 allow for the attachment ofthe camera 100 to external accessories or supports, such as a tripod.The strength provided by the magnesium also accommodates the weight ofthe lenses attached to the lens mount.

Rear housing component 104 is generally rectangular. Provided on theright side of the rear housing component 104 is an outlet 124, which isa tall slender opening in the housing wall. In front of the outlet 124is a forward column 133 that defines the front of the outlet 124.

Also on this side of the rear housing component 104 is a slot 120 inrear wall 135 for receiving a memory device, such as a memory card, orthe like. There is also provided a plug 122 for an audio input.

FIG. 2 shows a rear perspective view of the camera 100 showing theopposite left side of the camera. This side of the camera includes aninlet 128, which is identical to outlet 124 in appearance, being a tallslender opening defined on a front side by a column 133.

On the rear side 132 of the rear housing component 104 is a cut out area134 for receiving an externally mounted battery. The cut out area 134includes rails 136, which correspond to slots in the battery. Electricalcontacts 138 connect to the battery to provide power to the camera 100.A retractable clasp 140 is provided to lock into a slot in the back ofthe battery and hold the battery in the cut out area 134. The batteryslides vertically into the cut out area 134 from the top. The batterydepresses the clasp until fully inserted. The clasp 140 then extends andholds the battery in place. To release the battery, a slider 142 can beused, which retracts the clasp 140 allowing the battery to be slidupwards.

On the left side of the rear housing shown in FIG. 2 are two connectionports 142 on rear wall 135, which allow for the connection of cables toprovide power and/or data transfer.

FIG. 3 shows an alternative embodiment of the camera 100′ to that shownin FIGS. 1 and 2. Camera 100′ includes all of the features discussedabove in relation to camera 100, with the exception of the userinterface button 118. Camera 100′ may be a “broadcast” camera variant,that includes a limited user interface or internal memory and isremotely controlled. To this end, camera 100′ shown in FIG. 3 thereforeincludes connectors 142′, which communicate with an external interfaceand memory.

FIG. 4 is an exploded view of the components of the camera 100. At theforeground is the front housing component 102, which is as discussedearlier in relation to FIG. 1. It includes a lens mount 106 including amechanical structure configured to receive a mechanical coupling on alens to be fitted to the mount 106. The front housing component 102 alsoincludes a central bore 112 for admitting light to the optical systemmounted therein. Light indicator 116 and mounting point 119 are alsoprovided.

The front housing component 102 has a cylindrical front portion 144 anda generally rectangular rear portion 146. The sides 148 of the rearportion 146 are outwardly flared from a front face 150 to a rear edge152. Extending rearwardly from the rear edge 152 is a series of bosses154 for receiving fasteners (not shown) to secure the front housingcomponent 102 to the rear housing component 104.

Turning back to FIG. 1, when the front housing component 102 and therear housing component 104 are joined together, the outwardly flaredsides 148 of the front housing component 102 line up with the forwardcolumns 133 on the rear housing component 104. The rear walls 135 areinset from the flared columns 133 such that openings 128 and 124 areoriented on an angle. The benefit of this is that if the camera is laidon its side, the openings are not obstructed and air flow will bemaintained through the housing.

Light enters the camera 100 through an aperture 156 and passes throughan optical system and is received at an image sensor 158. The imagesensor 158 can include one or more devices which convert received lightto electrical signals, for example a charge coupled device (CCD) orcomplementary metal oxide semiconductor (CMOS) pixel sensor. In someembodiments this may be a 4K video format or higher resolution sensor,in others it will be HD, but, as will be appreciated, a person skilledin the art will be able to choose an image sensor having suitableoperational parameters (e.g. sensor size, resolution etc.) to suitrequirements.

An image sensor assembly 160 includes a substrate 162 which, in thisexample is a printed circuit board (PCB) substrate, which carries theimage sensor 158. The image sensor assembly 160 is mounted to the fronthousing component 102 via a series of screws (not shown). The screws areused to provide an adjustable mounting for the image sensor assembly 160when mounting it to the front housing component 102. The mounting canadditionally include one or more spacers such as shims 159 of thin metalor the like which can be used to adjust the positioning of the imagesensor assembly 160 with respect to the front housing component 102. Inparticular, it is important that the image sensor 158 is correctlylocated with respect to the central axis of the aperture 156 and thatits position in a forwards and backwards direction is set accuratelywith respect to the front mounting face of the lens mount 106. A seal163 is provided on the front of the image sensor assembly 160.

Located behind the image sensor assembly 160 is a first heat sink, beingan inlet-side heat sink 164. The inlet-side heat sink 164 has agenerally flat plate 166 and a series of fins 168 (best shown in FIG.5). The fins 168 extend generally perpendicularly from the rear side ofthe flat plate 166. A rim 170 also extends from the rear side of theflat plate 166 leaving a central cavity 172. On the front side of theflat plate 166 are a number of ribs 174 that allows space for a gap pad173 to be received as it is compressed between components. Theinlet-side heat sink 164 is made from die cast aluminum, however it willbe appreciated that other conductive materials and manufacturingtechniques may be utilised.

Heat from the image sensor 158 is thermally transferred to theinlet-side heat sink 164 via a copper block 161 and the gap pad 173 andany necessary thermal interface material such as thermal grease.Together, these components form part of the heat management system.

The heat management system can include a cooling subsystem 230 whichdraws heat away from the image sensor 158 in order to maintain correctoperation of the sensor. In a preferred form the temperature of theimage sensor is maintained at a constant level, hence it is preferableto use an active cooler, such as a Peltier cooler 230 that can vary itsheating and cooling effectiveness to suit variations in the temperaturelevel of the image sensor. The Peltier cooler 230 is mounted in thermalcontact with the rear side of the image sensor 158, via copper block161.

The image sensor 158 is very sensitive to temperature variation. It isfor this reason that the direction of air flow is such that the heatsink 164 that is thermally connected to the image sensor 158 is cooledfirst. Whilst the data processing unit 190 is a higher power componentand produces more heat, it is less sensitive to temperaturefluctuations. So whilst it is standard practice to design coolingsystems to prioritise cooling of the higher heat generating components,the present invention reverses that thinking in order to deliver a moreconstant temperature to the lower power component, being the imagesensor.

A spacer 180 is attached to the rear side of the inlet-side heat sink164. It will be appreciated that the spacer could also be attached to anoutlet-side heat sink. The spacer 180 is generally cylindrical, witharms 182 to allow the spacer to be screwed to the heat sink 164. A wall184 protrudes from the rear side of the spacer 180 and will be explainedfurther below. The spacer is made from a low thermally conductivematerial, such as plastic.

The joined spacer 180 and inlet-side heat sink 164 are fastened to thefront housing component 102 with screws that pass through apertures 186in the heat sink 164 and through apertures 188 in the sensor PCB 162.This clamps the heat sink 164 firmly against the rear of the imagesensor assembly 160. These components are stacked together in a singledirection to form a front section of the camera 100. It will beappreciated that alternative mounting arrangements may be utilised.

Housed within the rear housing component 104 is a data processing unit190. The data processing unit 190 includes a main PCB 192, which isprovided across two substrates 194, 196 that are connected at join 198.The main PCB includes a field programmable gate array (FPGA) 191 orother data processing system, such as a programmable micro controller,application-specific integrated circuit (ASIC) or the like, and is usedto process image data and control operation of the camera as will beknown to those skilled in the art.

In a most preferred embodiment the component of the data processing unit190 which generates the most heat, likely to be the FPGA 191 or otherprimary data processing element, is mounted so as to be exposed to or inthermal contact with, the front-most side 189 of the front substrate 194so that it can efficiently transfer heat to a second, outlet-side, heatsink 200.

The rear housing component 104 is made from a thermoplastic polymer,such as ABS. As strength is provided by the front housing component 102,the rear housing component can be from a material with a lower thermalconductivity. The rear housing component 104 will therefore not be ashot to touch and this is the part of the camera that a user is likely tohold.

In front of the data processing unit 190 is the outlet-side heat sink200. Similar to the inlet-side heat sink 164, the outlet-side heat sink200 includes a plate 202. On the front side of the plate 202 is a rim204, which includes a gap 206 to be described below. A series of fins208 extend generally perpendicularly from the front side of the flatplate 202 in fanned array. The inner ends 210 are closer together thantheir outer ends 212.

The outlet-side heat sink 200 is fastened to the data processing unit190 and then to the rear housing component 104. Side cover plates 214attach to the outlet-side heat sink 200 and the rear housing component104.

The outlet-side heat sink 200, the data processing unit 190 and the rearhousing component 104 are stacked together in one direction to form arear section of the camera 100.

The outlet-side heat sink 200 is made from aluminum or other suitablethermally conductive material and draws heat away from the dataprocessing unit 190.

The main PCB 192 connects to the image sensor assembly 160 via a ribboncable 220.

Placed in between the front section and rear section of the camera is afan 222. Fan 222 is a centrifugal fan, meaning one that draws airinwardly from an axial direction, and pushes it radially out the sidepast the tips 224 of the blades 226. The outlet-side heat sink fins 208are arranged tangentially to the fan blades 226 so the air does not haveto change direction to escape out the outlet 128. Together with theinlet-side and outlet-side heat sinks, the centrifugal fan forms part ofthe heat management system.

The centrifugal fan 222 includes arms 228 that are held in rubber boots229 that extend from the outlet-side heat sink 200. This holds thecentrifugal fan 222 inside the rim 204 and the rubber boots 229 limitvibration transfer. The centrifugal fan 222 is powered via cable 230,which projects through gap 206 in the rim 204 and connects back to themain PCB.

When clamped together, all the components are stacked in a singledirection, with the central cavity 17 on the inlet-side heat sink 164creating clearance in front of the fan 222 for airflow.

The use of a centrifugal fan 222 results in air flow space beingrequired in front of the fan, and in at least one lateral direction,i.e. in different dimensions. Thus the air is blown out the side of thestack of components, with the fins 208 of the outlet-side heat sink 200located in this direction. This is in contrast to an axial fan, whichrequires air flow space in front and behind a fan i.e. in the samedimension. The flow path through the centrifugal fan is advantageous inthat the direction of flow changes between its inlet and outlet. Thisallows the flow path to be routed through the camera in a spaceefficient manner.

Centrifugal fans are more space efficient than axial fans, as the inletand outlet can be more restricted. This is due to the fact that the rimon the inlet traps the air more effectively than the open blades of anaxial fan, once the air is past the rim it is trapped and spun to thetips of the blades. Axial fans are prone to re-circulation, unless theinlet and outlet are open and clear. Large industrial axial fans willpreferably be housed within a tube for this reason.

However, centrifugal fans work by building pressure rather than airflow. This results in lower flow and higher noise. For most cinemacameras airflow i.e. cooling capacity, and reduced noise are ratedhigher than space saving. The present invention inverts the priorities,whilst still managing to attain all the performance characteristics ofthis type of digital video camera. This ability to deal with smallerclearances enables the outlet to have heat sink fins located against it,with little loss of pressure.

A centrifugal fan 222 can be quite large given the overall size of thecamera housing. In the embodiment illustrated in FIGS. 1-9, the fan 222is 40 mm in diameter and 8 mm in thickness. The housing is around 65.4mm high, 82.5 mm wide and 69.5 mm deep. The large size allows for thecentrifugal fan to be operated at a relatively low speed. This reducesfan noise, and importantly reduces the amount of noise picked up by theuser and the microphones that are housed in the front housing component102.

In the embodiment illustrated in FIGS. 1 to 9, the centrifugal fan 222is positioned between the two heat sinks 164, 200. The centralrotational axis of the centrifugal fan 222 is generally perpendicular tothe line between the inlet 128 and the outlet 124. This is contrary tostandard arrangements, where an axial fan would require its axis to beparallel to the line between the inlet 128 and the outlet 124. Using acentrifugal fan in this orientation allows for a larger diameter fanthan if an axial fan were used. If access is required to the fan 222 forservicing or replacement, the front section and rear section can beseparated exposing the fan 222.

FIGS. 6 through 9 show various cross-sectional views through the camera100. These views show how all of the components are layered one behindthe other to create the high performance camera within a very smallouter housing.

As shown in FIGS. 6 and 9, the direction of the airflow is representedby arrow A. The rotation of the centrifugal fan 222 draws air throughthe inlet 128. The air then passes through the fins 168 on theinlet-side heat sink 164 into the central cavity 172 created by the rim170 of the inlet-side heat sink 164 in front of the fan 222. It will beappreciated that inlet-side heat sink 164 may not include fins 168.Alternatively, the depth of the fins 168 may be reduced so that they areonly provided to create a visually symmetrical pattern though inlet 128to the fins 208 seen through outlet 124. The heat from the image sensor158 passes into the inlet-side heat sink 164. As the air flows over theinlet-side heat sink 164 heat passes into the air, raising thetemperature of the air.

The air is drawn from the central cavity 172 into the fan blades 226 ina generally axial direction. Due to the restricted cavity 172 the airflow direction starts off as radial and bends to become axial as itenters the fan. The rim 204 on the inlet side of the outlet-side heatsink 200 and wall 184 of the spacer 180 prevents that air from escapinginto the rear of the camera housing. The rim traps the air andpressurises the air at the tips 226 of the fan blades 224. The heat fromthe data processing unit 190 passes into the outlet-side heat sink 200.The air changes direction and is pushed outwards by the tips 226 of thefan blades, directing the air radially across the fins 208 of theoutlet-side heat sink 200. The air then travels out of the housingthrough outlet 124.

FIG. 10 shows an alternative embodiment of the camera 400. In thisconfiguration there is a first heat sink 464 and a second heat sink 500positioned with a centrifugal fan 422. The first heat sink 646 and fan422 are aligned with the inlet 428 such that air flows through theinlet, through the first heat sink 464, into the front of the fan 422 inan axial direction. The second heat sink 500 is contained within a duct501. The duct 501 is L-shaped or curved such that a first end 503 of theduct 501 connects to the side of the centrifugal fan 422 and the heatsink fins 508 extend at a right angle. The inlet 428 and outlet 424 aretherefore on the same side of the housing and the air flow path isgenerally U-shaped. The advantage of this configuration is that arelatively slim width is achieved. Moreover, in a hand-held cameraapplication, this configuration puts the inlet and outlet on the sameside of the housing so they can be kept away from the user's hand, whichcan grasp the opposite side of the housing. As with the earlyembodiments, the first heat sink 464 is associated with the image sensor458. The second heat sink 500 is associated with the data processingunit 490.

FIG. 11 shows an alternative third embodiment of the camera 600. In thisconfiguration the centrifugal fan 622 is located after the first andsecond heat sinks 664, 700. There are inlets 628 provided on opposingsides of the housing adjacent the first heat sink 664. Air is then drawntowards the fan 622 in an axial direction through the second heat sink700. The air is then directed out the side of the fan 622 out the outlet624. The outlet 624 may be located on the same side as one of the inlets628 or on a side of the housing perpendicular to the inlets.

In both of the configurations shown in FIG. 10 and FIG. 11, the flowpath of air changes direction twice from the inlet to the outlet. One ofthese changes is due to the use of a centrifugal fan. The other is dueto the shape or orientation of the heat sinks.

In each of the configurations the centrifugal fan draws air into thefront of the fan in an axial direction and pushes air radially out in aside with direction such that the air flow path bends as it goes throughthe fan. The air travels over the first the sink associated with theimage sensor and then over the second heat sink associated with the dataprocessing unit.

It has been realised that a compact digital video camera can be designedthat utilises a cinema-quality image sensor by providing a stabletemperature for the image sensor rather than maximising cooling to thehigh power components. The use of a centrifugal fan allows maximisationof air flow, with relatively low noise, in a compact housing.

The present invention therefore allows for cinematographic levelcomponents, such as a 4K image sensor, to be contained within a verysmall housing. The reason this can be accomplished is througheffectively maintaining the temperature of the image sensor using acompact heat management system.

It will be understood that the invention disclosed and defined in thisspecification extends to all alternative combinations of two or more ofthe individual features mentioned or evident from the text or drawings.All of these different combinations constitute various alternativeaspects of the invention.

1. A digital video camera, including: a housing; at least one imagesensor to convert light into electrical signals; an optical systemassociated with the image sensor; a lens mount for releasably engaging alens or other optical module; data processing unit(s) to process imagedata received from the image sensor(s); and a heat management system,which includes: at least one inlet and at least one outlet in thehousing to enable air to flow through the housing; an inlet-side heatsink thermally connected to the image sensor(s), and an outlet-side heatsink thermally connected to the data processing unit(s), said inlet-sideheat sink being separated from the outlet-side heat sink; and a fanconfigured to draw air into the housing through the inlet(s) over theinlet-side heat sink and push air over the outlet-side heat sink out theoutlet(s); wherein the fan is a centrifugal fan, such that air is drawninto the front of the fan and pushed out one side of the fan.
 2. Adigital video camera, including: a housing; at least one image sensor toconvert light into electrical signals; an optical system associated withthe image sensor; a lens mount for releasably engaging a lens or otheroptical module; data processing unit(s) to process image data receivedfrom the image sensor(s); and a heat management system, which includes:at least one inlet and at least one outlet in the housing to enable airto flow through the housing; a first heat sink thermally connected tothe image sensor(s), and a second heat sink thermally connected to thedata processing unit(s); and a centrifugal fan configured to draw airinto the front of the fan in a generally axial direction and push airradially out in a sideways direction, whereby air is drawn into thehousing through the inlet(s) over the first heat sink and then over thesecond heat sink out the outlet(s).
 3. A digital video camera accordingto claim 2, wherein the first heat sink is an inlet-side heat sink andthe second heat sink is an outlet side heat sink.
 4. A digital videocamera according to claim 3, wherein the inlet-side heat sink isseparated from the outlet-side heat sink.
 5. A digital video cameraaccording to claim 2, wherein the centrifugal fan is located between thefirst heat sink and the second heat sink.
 6. A digital video cameraaccording to claim 1, wherein the housing is provided as two components,a front housing component and a rear housing component, and the inlet(s)and outlet(s) are provided on the rear housing component.
 7. A digitalvideo camera according to claim 2, wherein the inlet(s) and outlet(s)are openings located on opposing sides of the housing.
 8. A digitalvideo camera according to claim 2, wherein the housing is shaped suchthat the openings for the inlet(s) and outlet(s) cannot be obstructed bylaying the camera on either side.
 9. A digital video camera according toclaim 2, wherein a spacer is provided to physically separate the firstheat sink and the second heat sink.
 10. A digital video camera accordingto claim 9, wherein the spacer is made from a low thermally conductivematerial, to provide a thermal break between the first heat sink and thesecond heat sink.
 11. A digital video camera according to claim 9,wherein the spacer surrounds the centrifugal fan and includes a rim thatextends around the inlet-side of the spacer, to assist in trapping theair and pressurising the air at the tip of the fan blades to direct theair flow in the direction of the outlet(s).
 12. A digital video cameraaccording to claim 6, wherein the front housing component and rearhousing component are able to be separated so that the centrifugal fancan be exposed for removal allowing for repair or replacement.
 13. Adigital video camera according to claim 6, wherein the front housingcomponent also includes one or more microphones, positioned such thatthey are mechanically isolated from the fan to minimise noisetransmission through camera to the microphone's transducer.
 14. Adigital video camera according to claim 6, wherein the front housingcomponent is made from a stronger material than the rear housingcomponent.
 15. A digital video camera according to claim 14, wherein thefront housing component is made from magnesium.
 16. A digital videocamera according to claim 14, wherein the rear housing component is madefrom a plastic, such as a thermoplastic polymer.
 17. A digital videocamera according to claim 2, wherein the housing is provided as twocomponents, a front housing component and a rear housing component, andthe inlet(s) and outlet(s) are provided on the rear housing component.18. A digital video camera according to claim 17, wherein the fronthousing component and rear housing component are able to be separated sothat the centrifugal fan can be exposed for removal allowing for repairor replacement.
 19. A digital video camera according to claim 17,wherein the front housing component also includes one or moremicrophones, positioned such that they are mechanically isolated fromthe fan to minimise noise transmission through camera to themicrophone's transducer.
 20. A digital video camera according to claim17, wherein the front housing component is made from a stronger materialthan the rear housing component.
 21. A digital video camera according toclaim 10, wherein the spacer surrounds the centrifugal fan and includesa rim that extends around the inlet-side of the spacer, to assist intrapping the air and pressurising the air at the tip of the fan bladesto direct the air flow in the direction of the outlet(s).